Roller jewel protector for watch movements



Jan. 12, 1937. co Y 2,067,478

7 ROLLER JEWEL -BROTEGTOR FOR WATCH MOVEMENTS Filed July 2, 1935 v I Attorney Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE D Farrier Cormier, Welsh, La., assignor of one-half to John G. McClure, Welsh, La.

Application July 2, 1935, Serial No. 29,568

3 Claims.

This invention relates to a protector for roller jewels in watch movements.

In the present conventional watch construction the balance wheel normally makes a fraction of a revolution in one direction and then turns in the opposite direction for a part of a revolution. This movement imparts a rocking movement to the pallet fork through the medium of a roller jewel engaging in the fork on the end of the pallet fork. Although the balance wheel does not make a complete revolution in either direction it very often happens that the balance wheel will make a complete revolution contrary to its normal operation, in which case the roller jewel strikes the outer end of the prongs on the pallet fork in completing the revolution thereby injuring the roller jewel.

It is the primary purpose of the present invention to prevent the roller jewel from striking the edges of the prongs on the pallet fork by placing projections on each prong of the pallet fork that lie in the path of the roller table carried on the balance wheel staff to stop the roller and prevent damage to the roller jewel in event the balance wheel makes a complete revolution.

Further objects of the invention are to provide a protector for the roller jewel of the character referred to that is strong, compact and durable, very emcient for its intended purpose, adaptable for addition to the pallet fork without expensive alteration and that is comparatively inexpensive to manufacture and operate.

With the foregoing and other objects in view the invention consists of a novel construction, combination and arrangement of parts as will be hereinafter more specifically described and illustrated in the accompanying drawings wherein is disclosed an embodiment of the invention, but it is to be understood that changes, variations and modifications may be resorted to without departing from the spirit of the claims hereunto appended.

In the drawing wherein like reference characters denote corresponding parts throughout the several views:

Figure 1 is a fragmentary top plan view of a conventional watch movement showing the parts in assembled relation and illustrating an adaptation therewith of the protector in accordance with the present invention.

Figure 2 is a fragmentary enlarged top plan view of the bifurcated end of the pallet fork removed from the assembled watch movement.

Figure 3 is an enlarged side elevational view of the roller removed from the balance wheel staff and a fragmentary portion of the pallet in vertical section.

Figure 4 is a vertical section taken substantially on the line 4-4 of Figure 3.

Figure 5 is a top plan view of the roller table.

In the conventional practice of making watch movements the balance wheel 6 is formed with a. diametric spoke l and to the center of the spoke is fixed the balance wheel staff 8 on which the balance wheel rocks first in one direction for a part of a revolution and then rocks in the opposite direction for a part of a revolution. Under the balance wheel 6 there is an elongated plate 1 known as a roller table in the watchmakers parlance. The roller table 9 has a round opening ID on one end which encircles the balance wheel staff 8 and is fixed thereto. The other end of roller table 9 projects free of the spoke 1 and in the free end is mounted the roller jewel II which depends below the plane of the roller table. The roller jewel is segmental in cross section and the roller table 9 extends in a direction at right angles to the spoke 1.

Since the roller table 9 is fixed to the balance wheel staff 8 it rocks back and forth in response to the movement of the balance wheel. The rocking movement of the roller table 9 causes the pallet fork A to move back and forth and this movement of the pallet fork is translated to the escape wheel (not shown) in the customary manner. The pallet fork A is formed with a flat stem I2 which merges with a hub l3 to which is secured the pallet arbor l4. Projecting from the opposite sides of the hub l3 and in the same plane as the stem l2 are a pair of forked arms I5, I 6 in the ends of which are mounted the pallet stones l1, l8 that engage the teeth on the escapement wheel (not shown). The free end of the stem l2 terminates in a fork head with the prongs 20, 2| and a slot 22 between the prongs. The slot 22 opens outwardly between the prongs and has parallel side walls and an inner wall perpendicular to the side walls. Prongs 20, 2| terminate in points.

Under normal conditions the roller jewel Ii engages in the slot 22 whereby the oscillations back and forth of the balance wheel are translated to the pallet fork A. As heretofore explained, it sometimes happens that the balance wheel will make a complete revolution whereupon the roller jewel ll slips out of the slot 22 free of the bifurcated end of the stem l2. When this happens, the roller table in making a complete revolution will carry the roller jewel ll around until it strikes the edge of one of the prongs 20,

M which action usually injures the roller jewel.

To' overcome the injury to the roller jewel I place an upstanding pin 23 on one prong and an upstanding pin 24 on the other prong. These pins are preferably anchored at their lower ends to the prongs in any conventional manner. The pins 23, 24 are in transverse alignment with each other and are positioned from the ends of the prongs so as not to obstruct the roller jewel H as the latter moves out of the slot 22 but yet the pins lie in the path of the outer edges of the roller table so that the outer edges of the roller table will strike the pins and retain the roller jewel II in spaced relation to the edges of the prongs. From the lower ends of the pins where they are joined to the upper; face of the prongs these pins incline inwardly and upwardly and terminate below the bottom of the balance wheel 6. y

In conventional watch movement construction the plate or roller table 9 is flat and circular in outline. To' provide for the mounting and operation in the present construction, the plate or roller table 9 is flat and pear-shaped in con figuration.

Having thus described the invention, what is claimed as new is:

1. In an escapement mechanism having a balance wheel including a staff, roller table and roller jewel, a pallet fork comprising a bar bifurcated on one end to receive the roller jewel carried by the roller table mounted on the balance wheel staff, and a pair of upstanding pins on the bifurcated end of the bar one on each prong adapted to lie in the path of the roller table to prevent the roller jewel from striking the edge of the prongs.

2. The combination with a watch movement including an escapement mechanism including a balance wheel staff carrying a roller table and a pallet fork of a roller jewel connected with the roller table to move therewith, said pallet fork formed with a slot to receive the jewel, and the pallet fork carrying a projection on each side of the slot positioned to coact with the roller table to prevent the roller jewel from striking the sides of the pallet fork in event the oscillation of the balance wheel becomes excessive.

3. In a watch movement characterized by a roller table, a roller jewel mounted on the table, and a bifurcated pallet fork formed with a jewel receiving slot between the prongs of the pallet fork; the combination with the aforesaid elements of protector projections mounted on the prongs of the pallet fork one on each side of the slot positioned to coact with the roller table to prevent the roller jewel from striking the sides of the pallet fork in event the oscillation of the balance wheel becomes excessive.

his FARRIER CORMIER.

mark Witnesses to mark:

JorrN'G. McGLUaE, E. W. Duran. 

